Noisy 240Vac Fan on 12v Inverter
Submitted: Saturday, Oct 24, 2009 at 18:18
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PeterInSa
We occasionaly use a 240vac 30cm Desk fan on a 12volts Square wave inverter. SWMBO today purchased a 30cm Box Fan from B the giant Hardware chain and at $19.90 its great value. This fan is a lot easier to store for travellers and with sola don't have to use the genny.
Our convential fan made little noisy on 240 and on the inverter was around 3 times louder. The new box fan is around 5 times louder on 12v/300watt square inverter compared to 240vac. However its is around twice as loud on 240 as the convential desk fan (simialr speeds).
Neither fan gets hot when runing on 12v/Inverter. The noise is similar to that made from a big transformer used in some old soldering irons/old radios etc. and is probably coming from the coil laminations. I don't believe its a safety issue, any comments appreciated.
Have not tried it out on a Sine wave inverter
Peter
Reply By: Notso - Saturday, Oct 24, 2009 at 18:50
Saturday, Oct 24, 2009 at 18:50
Yeah mate it's the square wave that'll get em every time.
They expect a nice smooth transition in the AC ( Sine wave) and with the square wave introduces all sorts of new stuff that the motor isn't expecting.
AnswerID:
388532
Follow Up By: Member - Allan B (QLD) - Saturday, Oct 24, 2009 at 18:55
Saturday, Oct 24, 2009 at 18:55
Love that explanation Notso.
I would probably have used a page-and-a-half and left heads spinning!
But you have said it all.
FollowupID:
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Follow Up By: Notso - Saturday, Oct 24, 2009 at 19:03
Saturday, Oct 24, 2009 at 19:03
Yeah mate why do you think they called me Notso. Simple man simple language.
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Reply By: DIO - Saturday, Oct 24, 2009 at 19:43
Saturday, Oct 24, 2009 at 19:43
Have you considered a 12 volt van
Link so that you can do-away with the inverter.
AnswerID:
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Follow Up By: Maîneÿ . . .- Sunday, Oct 25, 2009 at 00:23
Sunday, Oct 25, 2009 at 00:23
I understand them to be 240v Fans running off the inverter ??
Maîneÿ . . .
FollowupID:
656221
Reply By: paulnsw - Saturday, Oct 24, 2009 at 23:50
Saturday, Oct 24, 2009 at 23:50
electric motors require sine wave
inverters
square wave or modified square wave
inverters cause problems as you have found out on motors. Motors will also use over 20% more power than sine wave inverter.
Your 30cm desk fan will have an asynchronous motor and the box fan a normal wound motor and the reason the difference in operational noise of the 2 fans. Both types are designed to run on sine wave but the asynchronous motor is a little more tolerant to square wave or modified square wave.
AnswerID:
388565
Reply By: Robin Miller - Sunday, Oct 25, 2009 at 07:57
Sunday, Oct 25, 2009 at 07:57
Hi Peter
Yep the electricity causes an electric field which
places force or the metal bits.
The squarer wave switching causes a greater rate of change of electric field and has imparts more force.
This has both advanatges and disadvantages and usually results in more noise.
I do same thing and being aware of the issue I brought a small 120w 12v MSW inverter as
well (fits in the plam of your hand and they were only $14.95).
The % load on the little one is larger and tends to round off the square wave a bit making less noise.
The result is that when our fan is on low you can hear an increase in noise but when its on high the difference is so small as to be swamped by the fan noise anyway and overall its not an issue.
P.S. When we run our microwave off our 1500w MSW inverter the rattle is louder than a toyota diesel starting up cold.
AnswerID:
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Follow Up By: PeterInSa - Sunday, Oct 25, 2009 at 20:09
Sunday, Oct 25, 2009 at 20:09
Robin,
Where did you buy the 120w MSW for $14.95?
SWMBO does not mind the noise at all, now if I had purchased it....
Peter
FollowupID:
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Follow Up By: PeterInSa - Wednesday, Oct 28, 2009 at 16:26
Wednesday, Oct 28, 2009 at 16:26
Thanks
Peter
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Reply By: Maîneÿ . . .- Sunday, Oct 25, 2009 at 09:46
Sunday, Oct 25, 2009 at 09:46
Looks like the above posts contain clear points to consider before buying a 'square wave' or 'modified square wave' type inverter, instead of buying the more expensive Pure Sine Wave inverter ?
Maîneÿ . . .
AnswerID:
388588